U.S. patent application number 15/015167 was filed with the patent office on 2017-08-10 for indication of vehicle direction of travel.
The applicant listed for this patent is Ford Global Technologies, LLC. Invention is credited to XIAOYONG WANG, Hai Yu.
Application Number | 20170225710 15/015167 |
Document ID | / |
Family ID | 59382607 |
Filed Date | 2017-08-10 |
United States Patent
Application |
20170225710 |
Kind Code |
A1 |
Yu; Hai ; et al. |
August 10, 2017 |
Indication of Vehicle Direction of Travel
Abstract
A vehicle may include a processor programmed to control
operation of the vehicle. The processor may control operation of
the vehicle according to an indication of a direction of travel.
The indication of direction of travel may be based on signs of data
representing jerk of the vehicle. The signs of data representing
jerk may be derived from acceleration and speed sensor outputs. The
indication may be such that the indication is reverse in response
to the signs being opposite when the vehicle is in a forward drive
gear.
Inventors: |
Yu; Hai; (Canton, MI)
; WANG; XIAOYONG; (Novi, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ford Global Technologies, LLC |
Dearborn |
MI |
US |
|
|
Family ID: |
59382607 |
Appl. No.: |
15/015167 |
Filed: |
February 4, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B62D 15/025 20130101;
B60W 30/20 20130101; B60W 30/06 20130101; B60W 2510/1005 20130101;
B60W 2520/06 20130101; B60W 2520/10 20130101; B60W 2520/105
20130101; B60W 30/18045 20130101; B60W 2050/0052 20130101 |
International
Class: |
B62D 15/02 20060101
B62D015/02; B60W 30/06 20060101 B60W030/06 |
Claims
1. A vehicle comprising: a processor programmed to control
operation of the vehicle according to an indication of a direction
of travel that is based on signs of data representing jerk of the
vehicle derived from acceleration and speed sensor outputs such
that the indication is reverse in response to the signs being
opposite when the vehicle is in a forward drive gear.
2. The vehicle of claim 1, wherein the indication is forward in
response to the signs being same when the vehicle is in a reverse
gear.
3. The vehicle of claim 1, wherein the processor is further
programmed to apply a band-pass filter to the data to remove
frequency content indicative of road grade variation.
4. The vehicle of claim 1, wherein controlling operation of the
vehicle includes executing an automatic steering command.
5. The vehicle of claim 1, wherein controlling operation of the
vehicle includes executing an automatic parking command.
6. A method comprising: by a controller of a vehicle, generating a
reverse indication of direction of travel in response to signs of
data representing jerk derived from acceleration and speed sensor
outputs being opposite when the vehicle is in a forward drive gear;
and controlling operation of the vehicle according to the reverse
indication.
7. The method of claim 6 further comprising generating a forward
indication of direction of travel in response to the signs being
same when the vehicle is in a reverse gear.
8. The method of claim 6 further comprising applying a band-pass
filter to the data to remove frequency content indicative of road
grade variation.
9. The method of claim 6 further comprising executing an automatic
steering command based on the indicated direction of travel.
10. The method of claim 6 further comprising executing an automatic
parking command based on the indicated direction of travel.
11. A vehicle comprising: a processor programmed to execute
automatic steering commands according to a forward indication of
direction of travel that is generated in response to signs of data,
representing jerk of the vehicle derived from acceleration and
speed sensor outputs, being same when the vehicle is in a reverse
gear.
12. The vehicle of claim 11, wherein the processor is further
programmed to execute automatic steering commands according to a
rearward indication of direction of travel that is generated in
response to signs of data, representing jerk of the vehicle derived
from acceleration and speed sensor outputs, being opposite when the
vehicle is in a forward drive gear.
13. The vehicle of claim 11, wherein the processor is further
programmed to apply a band-pass filter to the data to remove
frequency content indicative of road grade variation.
14. The vehicle of claim 11, wherein the automatic steering
commands park the vehicle.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to vehicle direction of
travel indication.
BACKGROUND
[0002] A vehicle control system may obtain speed indication from a
brake system module or other module designed to interpret wheel
speed sensor output. Wheel speed sensors are generally direction
independent. That is, directional information does not accompany
speed indication. Consequently, vehicle direction is typically
determined using additional sensors or transmission status. These
direction detection methods may continue to provide incorrect
information or add cost.
SUMMARY
[0003] A vehicle may include a processor programmed to control
operation of the vehicle. The processor may control operation of
the vehicle according to an indication of a direction of travel.
The indication of direction of travel may be based on signs of data
representing jerk of the vehicle. The signs of data may be derived
from acceleration and speed sensor outputs. The indication may be
such that the indication is reverse in response to the signs being
opposite when the vehicle is in a forward drive gear.
[0004] The indication may be forward in response to the signs being
same when the vehicle is in a reverse gear. The processor may be
further programmed to apply a band-pass filter to the data to
remove frequency content indicative of road grade. The processor
may control operation of the vehicle by executing an automatic
steering command. The processor may control operation of the
vehicle by executing an automatic parking command.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is an overview of a vehicle having a direction
indication system.
[0006] FIG. 2 is a functional diagram for a vehicle direction
indication system.
[0007] FIG. 3 is a flow diagram of a vehicle direction indication
using speed and acceleration sensor outputs.
[0008] FIG. 4 is an output chart of a vehicle direction indication
system depicting generally same signs.
[0009] FIG. 5 is an output chart of a vehicle direction indication
system depicting generally opposite signs.
[0010] FIG. 6 is an output chart of a vehicle direction indication
system oscillating between same and opposite signs.
[0011] FIG. 7 is an input and output chart of a vehicle direction
indication system having a direction correction system.
DETAILED DESCRIPTION
[0012] Embodiments of the present disclosure are described herein.
It is to be understood, however, that the disclosed embodiments are
merely examples and other embodiments may take various and
alternative forms. The figures are not necessarily to scale; some
features could be exaggerated or minimized to show details of
particular components. Therefore, specific structural and
functional details disclosed herein are not to be interpreted as
limiting, but merely as a representative basis for teaching one
skilled in the art to variously employ the present invention. As
those of ordinary skill in the art will understand, various
features illustrated and described with reference to any one of the
figures may be combined with features illustrated in one or more
other figures to produce embodiments that are not explicitly
illustrated or described. The combinations of features illustrated
provide representative embodiments for typical applications.
Various combinations and modifications of the features consistent
with the teachings of this disclosure, however, could be desired
for particular applications or implementations.
[0013] Vehicle longitudinal direction may be used by vehicle
control systems or occupants to properly control a vehicle. For
example, a vehicle may use longitudinal direction to initiate
parking commands or steering commands. A vehicle may also use
longitudinal direction to increase or decrease fuel injection.
Transmission status may provide adequate indication of vehicle
longitudinal direction under certain circumstances. Transmission
status, however, may improperly indicate longitudinal direction
when a vehicle is on an incline opposite the intended direction of
travel. For instance, a vehicle directed uphill on a slope and in a
drive or forward gear may travel in a reverse direction if the
transmission creep cannot overcome opposing forces. A vehicle
controller having speed and acceleration sensor inputs may correct
erroneous indications by generating a reverse indication or
affirming a proper indication.
[0014] Vehicles may include systems to determine speed. A vehicle
speed sensor may use magnetic, electric, or optic effects to
determine rotations of the wheel, movement in relation to ground,
or GPS indication of speed. Any method of speed indication may be
used to correct erroneous indications of vehicle longitudinal
direction. For instance, the circumference of the wheel and the
rotations of the wheel may be used to determine the vehicle
longitudinal speed. Vehicles may also include systems to determine
acceleration of the vehicle. The accelerometer or acceleration
sensor may be of any type (e.g., capacitive, piezoelectric,
piezoresistive, Hall Effect, magnetoresistive, etc.).
[0015] The outputs to these systems may be fed into a control
system configured to interpret the provided digital or analog
values. The controller or processor of the control system may
manipulate these values to determine a direction of travel for the
vehicle. A relationship between speed, acceleration, and jerk, may
be utilized by comparing the sign of each jerk value to determine
the direction of travel. Just as acceleration is the time
derivative of velocity, jerk as used herein is the time derivative
of acceleration. Numerical methods may be used to determine the
time derivatives of both the velocity and the acceleration to
result in two separate values for jerk. If for example the signs
are opposite, the determined direction of travel would be reverse
even though the vehicle may be in a forward drive gear if rolling
backward down a hill. Likewise if the signs are the same, the
determined direction of travel would be forward even though the
vehicle may be in a reverse gear if rolling forward down a
hill.
[0016] Numerical methods or approximations, such as Runge-Kutta,
Euler's method, etc., may be used to provide a numerical
approximation of the rate of change for the speed and acceleration
sensors. A time step for the derivative computation may be near 5
ms or as large as 20 ms. Accuracy of the numerical approximation
may be improved by reducing the time step, but may require more
processing power.
[0017] Using these numerical methods a jerk value may be obtained
for the speed sensor output and the accelerometer output. Once a
value for jerk for each of the sensors is obtained, a band-pass
filter may be used to remove unwanted frequency content from the
sensor value. A digital bandpass filter may be defined by a
z-transfer function a depicted in Equation 1. The band-pass filter
may be used to remove the low frequency information from the
signal, which may be indicative of the vehicle resting on an
incline, and high frequency information from the signal, which may
be indicative of instrument noise. Analog or digital filters may be
used depending on the input type. For example, a biquad bandpass
filter having a transfer function similar to Equation 1 may be
used.
H = ( z + 1 ) ( z - 1 ) z 2 - 2 r ( cos .PHI. ) z + r 2 Equation 1
##EQU00001##
[0018] A preferred passband may be between 1-15 Hz for certain
vehicles and 5-20 Hz for other vehicles. A vehicle may be tested at
the factory to determine a preferred passband because threshold
values vary among different vehicles. Any type of transfer function
may be used to remove unwanted frequency content from the sensor
jerk values. As is well known in the art, analog systems may be
used instead of digital or discrete systems to implement the
bandpass filter.
[0019] Referring now to FIG. 1, a vehicle direction indication
system 100 is shown. A vehicle 105 may include a controller 110
connected, directly or indirectly, to at least one speed sensor 115
and at least one acceleration sensor or accelerometer 120. The
speed sensor 115 may be a hall sensor having a magnetic pickup
located on the axle or wheel housing of the vehicle. The speed
sensor 115 may be electrically connected to the controller 110,
sending digital or analog data to be processed. The acceleration
sensor 120 may be electrically connected to the controller 110,
sending digital or analog data to be processed.
[0020] Now referring to FIG. 2, a functional diagram 200 is
depicted. The functions included therein may be performed on a
controller or processor located within the vehicle or off board as
is known in the art. The input from the speed sensor 202 and
acceleration sensor 204 are received by a controller. A numerical
method 206 may be applied to the speed sensor input 202 to
determine the second derivative of the speed signal 202, known as
jerk, and similarly applied to the acceleration sensor input 204 to
determine the first derivative of the acceleration signal 204, also
known as jerk. The jerk values for both the speed and acceleration
inputs 202, 204 are filtered through digital signal processing 208
to remove frequencies not within the specified band. The resulting
sign of the value is compared at function 210 to determine the
direction of travel. A native vehicle speed input 212, which may be
the same as the vehicle speed input 202, is given a directional
component from the direction of travel determined at function 210
at arithmetic function 214. The vehicle vector is then supplied to
the vehicle control system 216.
[0021] Now referring to FIG. 3, an algorithm 300 is depicted. Step
302 is the start point of the algorithm. The vehicle speed is
detected at step 304. The vehicle acceleration is detected at step
310. At step 306, a numerical model may be applied to the vehicle
speed input to determine a jerk value derived from the vehicle
speed. At step 312 a numerical model may be applied to the vehicle
acceleration input to determine a jerk value derived from the
vehicle acceleration. At step 308 a filter may be applied to the
jerk data determined in step 306 to remove high or low frequency
content from the data. At step 314 a filter may be applied to the
jerk data determined in step 312 to remove high or low frequency
content from the data. At step 316 a comparison between the sign of
the vehicle speed data and the sign of the vehicle acceleration
data is performed. If the sign of the vehicle speed is not equal to
the sign of the vehicle acceleration, the vehicle direction is
updated in step 320 to reverse. If the sign of the vehicle speed is
equal to the sign of the vehicle acceleration, the vehicle
direction is updated in step 318 to forward. Then the algorithm
returns to step 302.
[0022] Now referring to FIG. 4, a chart 400 depicting a speed
indication (V.sub.x), jerk data derived from a speed sensor output
({umlaut over (V)}.sub.x.sup.h), and jerk data derived from an
acceleration sensor output (A.sub.x.sup.h) is shown. The speed
indication V.sub.x does not include directional information,
meaning V.sub.x is always a positive real number until direction
indication is derived. A direction indication relative to the
vehicle being in drive is depicted in the sub-chart. From the left
side of the chart the sign of {umlaut over (V)}.sub.x.sup.h is
different from the sign of A.sub.x.sup.h because until about time
of 39 seconds {umlaut over (V)}.sub.x.sup.h is zero and
A.sub.x.sup.h is greater than or less than zero. Up until time of
39 seconds the direction wrong indication is set to "1" or "TRUE."
After the 39-second mark the sign of both {umlaut over
(V)}.sub.x.sup.h and A.sub.x.sup.h are equal and the direction
wrong indication falls to "0" or "FALSE" regardless of the vehicle
speed.
[0023] Now referring to FIG. 5, a chart 500 depicting a speed
indication (V.sub.x), jerk data derived from a speed sensor output
({umlaut over (V)}.sub.x.sup.h), and jerk data derived from an
acceleration sensor output (A.sub.x.sup.h) is shown. The initial
condition of the direction indication is that the direction is
correct. At about the 18-second mark 502 a discrepancy between the
signs of {umlaut over (V)}.sub.x.sup.h and A.sub.x.sup.h occurs
indicating an incorrect direction. As shown in larger detail at
points 504, 506, and 508, the signs of the {umlaut over
(V)}.sub.x.sup.h and the A.sub.x.sup.h values are opposite, which
indicates a wrong direction situation.
[0024] Now referring to FIG. 6, a chart 600 depicting a speed
indication (V.sub.x), jerk data derived from a speed sensor output
({umlaut over (V)}.sub.x.sup.h), and jerk data derived from an
acceleration sensor output (A.sub.x.sup.h) is shown. At point 602 a
warning for improper speed indication is shown. The warning may be
determined by an abrupt change in the jerk value, as derived. Near
the 20-second mark and until the 40-second mark, at area 604, the
signs of {umlaut over (V)}.sub.x.sup.h and A.sub.x.sup.h become
opposite and a direction wrong signal is indicated. Around the
40-second mark the signs become equal, at area 606, until about the
50-second mark. As shown in area 608, the signs of {umlaut over
(V)}.sub.x.sup.h and A.sub.x.sup.h are opposite, denoting a wrong
direction indication.
[0025] Now referring to FIG. 7, a chart 700 depicting a raw speed
indication (V.sub.x raw), a corrected speed indication (V.sub.x
corrected), and a direction correction indication. As shown until
about the 20-second mark 702, the V.sub.x raw and V.sub.x corrected
signals are equal. At about the 20-second mark 702 the direction
correction flips to indicate that the V.sub.x raw signal is
incorrect. Until about the 40-second mark 704 the V.sub.x corrected
signal is used, as an inverse of the V.sub.x raw signal, to provide
the vehicle control system with a velocity including speed and
direction.
[0026] The processes, methods, or algorithms disclosed herein may
be deliverable to or implemented by a processing device,
controller, or computer, which may include any existing
programmable electronic control unit or dedicated electronic
control unit. Similarly, the processes, methods, or algorithms may
be stored as data and instructions executable by a controller or
computer in many forms including, but not limited to, information
permanently stored on non-writable storage media such as ROM
devices and information alterably stored on writeable storage media
such as floppy disks, magnetic tapes, CDs, RAM devices, and other
magnetic and optical media. The processes, methods, or algorithms
may also be implemented in a software executable object.
Alternatively, the processes, methods, or algorithms may be
embodied in whole or in part using suitable hardware components,
such as Application Specific Integrated Circuits (ASICs),
Field-Programmable Gate Arrays (FPGAs), state machines, controllers
or other hardware components or devices, or a combination of
hardware, software and firmware components.
[0027] The words used in the specification are words of description
rather than limitation, and it is understood that various changes
may be made without departing from the spirit and scope of the
disclosure. As previously described, the features of various
embodiments may be combined to form further embodiments of the
invention that may not be explicitly described or illustrated.
While various embodiments could have been described as providing
advantages or being preferred over other embodiments or prior art
implementations with respect to one or more desired
characteristics, those of ordinary skill in the art recognize that
one or more features or characteristics may be compromised to
achieve desired overall system attributes, which depend on the
specific application and implementation. These attributes may
include, but are not limited to cost, strength, durability, life
cycle cost, marketability, appearance, packaging, size,
serviceability, weight, manufacturability, ease of assembly, etc.
As such, embodiments described as less desirable than other
embodiments or prior art implementations with respect to one or
more characteristics are not outside the scope of the disclosure
and may be desirable for particular applications.
* * * * *